1. Field of the Invention
The present invention relates to a start control technique for controlling starting of a vehicle based on a signal received from a remote terminal or in the directive mode.
2. Description of the Related Art
A vehicle generally has a starter switch to control starting of an engine of the vehicle, an ignition switch to control ignition of the engine, and an accessory switch to control on/off of an in-vehicle electric equipment.
When the starter switch is ON, large amount of power is required to rotate a starter motor. Therefore, when the starter switch and the accessory switch are turned ON simultaneously, enough power may not be supplied to the in-vehicle electric equipment.
To solve this problem, conventionally, a configuration has been employed in which the ignition key is mechanically operated by the operator to turn ON or OFF the switches (a starter switch, an ignition switch, and accessory switches), so that the starter switch and accessory switches do not turn ON simultaneously.
Recently, however, vehicles can be stared with a remote operation terminal, such as a remote key, i.e., without using an ignition key. In such a case, a relay circuit is used to perform ON/OFF control of the ignition switches, such as the starter switch, the ignition switch, and the accessory switches.
However, because the starter switch and the accessory switch control a larger current, contact welding can occur in a switch (a control relay) of these switches. If contact welding occurs, the starter switch and the accessory switch can simultaneously turned ON.
Japanese Utility Model Publication No. 2573274 discloses a technique to turn OFF other control relays when contact welding occurs in a switch (a control relay) and then turning OFF a sub-relay shared by each switch. Japanese Patent Laid-Open Publication No. H9-329074 discloses an engine starter with enhanced capability for detecting trouble in bypassing a start contact in a contact unit.
In the conventional techniques, however, a sub-relay is turned OFF after contact welding is detected and other switches are turned OFF, so that is a time lag until power to the switch, in which the contact welding has occurred, is disconnected.
As a result, the starter switch and the accessory switch may be simultaneously turned ON, in-vehicle electric equipment may be affected by noises, and the starter motor may operate even after start of an engine is completed.
Sometimes it may be desirable to continue usual operations, even when welding occurs, without disconnecting all the switches. For instance, when welding occurs in the starter switch, it is preferable that only the starter switch is disconnected and usual operations of the accessory switch or the ignition switch are continued.
In the conventional techniques, however, when welding occurs in any switch, even the other switches are disconnected before disconnecting the shared sub-relay. As a result, ordinal control can not be continued even in switches in which welding has not occurred.
In some vehicles, a plurality of ignition or starter signals are used. In this case, it is necessary to provide a corresponding number of ignition switches or starter switches in the start control apparatus. However, production cost increases in preparing two types of start control apparatuses: one for vehicles that use only one signal and one for vehicles that use a plurality of signals. Thus, there is need to develop a versatile start control apparatus that can be used in both type of vehicles.
Moreover, from the view point of cost reduction, it is desirable that switches that are not necessary are not provided, and that switches can be provided only when required.
However, when a start control apparatus capable of corresponding to starter signals for two signal lines is loaded in a vehicle having only one signal line, if switches that not used are simply removed, an abnormal state is generated when there is a need to determine a state of the removed switches.
Determination of state of a switch includes open determination and welding determination. Open determination includes determining whether the switch is open (i.e., whether the switch is correctly turned ON in response to control for turning the switch ON). Welding determination includes determining whether welding has occurred (i.e., whether the switch is correctly turned OFF in response to control for tuning the switch OFF). In the case of the removed switch, the result of the determination of its state is always the same, i.e., OFF, so that the result of the open determination always indicates that there is open trouble (i.e., the switch is OFF irrespective of control for turning the switch ON).
There is a need for development of a start control apparatus and a start control method having high applicability irrespective of configuration of the vehicles and capable of accurately determining a state of a switch with simple configuration.